//
/***********************************************************
             File name:      main.c
             Author:         Bitat (陆叁柒)
             Email :         Bitat@qq.com
             Gitee :         https://gitee.com/bitat
             CSDN  :         https://blog.csdn.net/bitat 
             History:        2023/2/12
************************************************************/

#include<stdio.h>

int fact(int n)
{
    if(n==1)
    {
        return 1;
    }
    else
    {
        return n*fact(n-1);
    }
}

int main()
{
     int x;
     scanf("%d",&x);
     x = fact(x);
     printf("%d\n",x);
    
    return 0;
}
